Load adaptive power delivery

ABSTRACT

Embodiments disclosed herein include a power monitor and controller which are used to control the operation of a voltage regulator depending on an operating mode or state of a load device, such as a hard disk drive. By controlling the voltage regulator in this manner, voltage regulator efficiency may be improved for any load condition, thus reducing power losses in the system.

BACKGROUND

1. Field

Embodiments of the present invention relate to the field of powerdelivery for computing devices and more specifically to adaptive powerdelivery to control and manage power efficiency for one or more devicesin a system.

2. Discussion of Related Art

A typical example of a power delivery network is shown in FIG. 1. A harddisk drive (106) is directly powered by a voltage regulator (104). Thevoltage regulator converts the system supply voltage (102) to theappropriate voltage level (Vcc) required by the hard disk drive underits entire load current range (Icc).

Power consumption of a hard drive varies from time to time during itsoperation. Table 1, below, illustrates the power consumed during variousstages of operation by a 1.8 inch Toshiba® MK2004 hard disk driverequiring a supply voltage of 3.3V±5%:

TABLE 1 Power consumption of a hard disk drive Operating Mode AveragePower Start 1.2 W Seek 1.4 W Read/Write 1.4 W Active Idle 0.6 W LowPower Idle 0.4 W Standby 0.2 W Sleep 0.08 W 

Even though the drive operates at a single fixed voltage level, its loadpower or current changes by approximately 2× from the start mode toactive idle. There is nearly a 10× change in power consumption fromactive idle mode to sleep mode.

A typical voltage regulator (104) may be designed to optimize itsperformance at a single maximum load point, Icc_MAX. Thus, for all otheroperating loads, the performance of the voltage regulator may be lessefficient. Typically the efficiency of the voltage regulator is 30-50%less at a light load (e.g. less than 10% of Icc_MAX).

FIG. 2 is a graph (200) illustrating the power efficiency of an examplevoltage regulator across a range of load currents. The example voltageregulator is most efficient at the maximum load current, Icc_MAX, and isless efficient at loads less than Icc_MAX. Region 202 indicates a regionof lower load current operation, such as in the active idle, low poweridle, standby, or sleep modes, where power efficiency may be lower thanthe maximum efficiency. Thus, in some modes there may be power losscaused by the inefficiency of the VR, which can lead to shorter batterylife in a battery powered system.

BRIEF DESCRIPTION OF THE DRAWINGS

An understanding of embodiments of the present invention can be obtainedfrom the following detailed description in conjunction with thefollowing drawings, in which:

FIG. 1 is a block diagram illustrating a typical power delivery network.

FIG. 2 is a graph which illustrates power efficiency versus load currentfor a typical power delivery network.

FIG. 3 is an illustration of a block diagram of a power delivery systemaccording to some embodiments.

FIG. 4 is an illustration of a block diagram of a power delivery systemaccording to some embodiments.

FIG. 5 is a flow diagram illustrating a method according to someembodiments.

FIG. 6 is a graph illustrating power efficiency versus load currentaccording to some embodiments.

DETAILED DESCRIPTION

A method, system, and apparatus to reduce voltage regulator power lossand increase power efficiency are described herein. In the followingdescription, for purposes of explanation, numerous specific details areset forth in order to provide a thorough understanding of embodiments ofthe present invention. However, it will be apparent to one skilled inthe art that these specific details are not required in order topractice embodiments of the present invention.

Embodiments disclosed herein include a power monitor and controllerwhich are used to control the operation of a voltage regulator dependingon an operating mode or state of a load device, or power consumption ofthe device. By controlling the voltage regulator in this manner, voltageregulator efficiency may be increased for any load condition, thusreducing power losses in the system.

FIG. 3 illustrates a system (300) to adjust and control power deliverybased at least in part on one or more of load demand and/or device powerstate according to some embodiments. The system (300) may include atleast a processor or CPU (350), memory controller device (352), I/Ocontroller device (358), and one or more memory devices (354). Note thatin some embodiments, the memory controller device and/or the I/Ocontroller device may be integrated into the CPU/processor.

The system may also include a network port or interface (360), and maybe coupled to a wired or wireless network (362). The memory controllerdevice (352) may be coupled to the CPU (350) by a bus or interconnect(351). The memory controller device (352) provides the CPU (350) withaccess to one or more memory devices (354), to which the memorycontroller device (352) is coupled by a memory bus or interconnect(353).

A graphics processing unit (356) may be coupled to the memory controllerdevice via a bus or interconnect (355). An I/O controller hub (358) maybe coupled to the memory controller device (352) by a bus orinterconnect (357). The I/O controller hub (358) may be coupled to anetwork port (360), capable of connecting to a network (362). The I/Ocontroller hub (358) may also be coupled to a storage device (314),which in some embodiments may be a hard disk drive. A battery or otherpower source (302) may provide power to the storage device (314), andmay provide power to the entire system. For ease of understanding, thepower delivery and voltage regulation scheme is shown only for a singledevice (314), and is not illustrated for the other components in thesystem.

Together, these components form a system (300) that is capable ofsupporting the execution of machine readable instructions by CPU (350),and the storage of data, including instructions, within memory devices(354). One or more components in the system may be powered by a powersource (302) in conjunction with a voltage regulator (304), optionalinput sense circuit (318), output sense circuit (320) and device statusmonitor (316).

The voltage regulator (304) may include an input filter (306), powerstages (308), and an output filter (310). Power is provided to thevoltage regulator by a power source (302), which may be a battery oranother type of power supply. The voltage regulator supplies an outputvoltage (Vcc) to the load device (314) at an output current (Icc).

The voltage regulator may also include a controller (312) to determinean operating mode for the voltage regulator. The controller may receivethe output voltage and current of the voltage regulator (Vcc, Icc) froman output sense circuit (320). In some embodiments, the controller mayalso receive an input power, P_(in), from an input sense circuit (318).The controller (312) may also receive load information from a devicestatus monitor (316), which is coupled to a load device (314). In someembodiments, the load device may be any device having a variable load.For example, the device may be, but is not limited to, a hard diskdrive, an optical drive, a display, a processor or other electroniccomponent, or a system.

The device status monitor (316) may store information related to theoperation and/or power consumption of the device (314). For example, thedevice status monitor information may include the current operationalmode or power state of the device, the upper and lower boundaries of thedevice's power consumption, and the estimated time period the device isexpected to stay in its present state. The device status monitor maymonitor other device properties as well.

In some embodiments, the device sense monitor or monitors (316) may beimplemented as a register or set of registers, or as an EPROM. Theinformation stored by the device sense monitor may be stored in the formof a static look-up table. In other embodiments, the information storedby the device status monitor may be updated dynamically, as the systemruns. Furthermore, the controller (312) may dynamically monitor/sensethe power input (318) and output (320) to determine the best or optimaloperational mode based on power efficiency using multiple sense monitors(input and output). In this case, a device status monitor may not berequired.

The controller may receive information regarding the device'soperational status and/or power consumption from the device statusmonitor. This information may include, but is not limited to, thecurrent operational mode or power state of the device, the upper andlower boundaries of the device's power consumption, and/or the estimatedtime period the device is expected to stay in its present state. Thecontroller may use this information in conjunction with the actualsensed Vcc/Icc to generate one or more control signals to control theoperation of the power stage of the voltage regulator. In someembodiments, the controller may include a timer (313) to adjust the modeof operation of the voltage regulator based upon the estimated timeperiod the device is expected to stay in its present state.

Dynamically adjusting the operating mode of the voltage regulator basedon the power requirements of the device may allow the voltage regulatorto achieve increased efficiency across multiple load conditions.

In some embodiments, such as shown in FIG. 3, the controller (312) maybe part of the voltage regulator. FIG. 4 illustrates another embodiment,wherein the controller (312) may be separate from the power conversioncircuitry (343).

The controller (312) may be a part of a load adaptive controller (345),which may include an input sense circuit (318), output sense circuit(320), and a status monitor (316). In some embodiments, the controller(312) and/or the load adaptive controller (345) may be an applicationspecific integrated circuit (ASIC). The controller (312) and/or loadadaptive controller (345) may further be integrated with anothercomponent, such as a chipset or processor, or may be integrated with thepowered device (314).

Similarly, the device status monitor (316) may be a discrete component,such as an ASIC, or may be integrated into another component such as achipset. In some embodiments, the device status monitor (316) may beintegrated into the same component as the controller (312), such as in aload adaptive controller (345).

FIG. 5 is a flowchart illustrating a load adaptive power deliveryapproach according to one embodiment. Upon system power up (502), avoltage regulator may initially be in a full power mode, due to theuncertain behavior of the load device at power up. The controller maythen receive device information from the device status monitor (504),and may sense the voltage regulator input and/or output supplies(P_(in), Vcc, Icc) (506).

The controller may use the device information in conjunction with the VRsupply information to determine an appropriate operating mode for thevoltage regulator (508). The operational mode of the voltage regulatormay be chosen to improve power efficiency based on load demandconsiderations indicated by the device status monitor.

If the voltage regulator is not operating in the appropriate mode, thenan operating mode change may be necessary (510). If the voltageregulator is operating in the appropriate mode, the controller maycontinue to monitor the device information (504) and supplies (506) todetermine if/when an operating mode change is appropriate (508).

In some embodiments, the controller may include pre-defined operationalmode adjustment sequences that correspond to known device behaviors. Forexample, the behavior and power requirements of a hard disk drive onwake up are generally known and understood. Thus, when the controllerdetects that the hard disk drive has entered a wake up state, thecontroller may use a predefined wake up sequence to control the voltageregulator during the hard drive wake up state. The use of predefinedoperational mode sequences which correspond to known device states mayreduce the complexity of the controller design and increase efficiency.

After the controller has determined a proper operational mode for thevoltage regulator, it may then direct the voltage regulator to eitherremain in its current mode of operation, or transition up or down to anappropriate mode of operation (512). The controller may output a signalto the voltage regulator to change the VR operating mode, or may controlthe mode of operation of the voltage regulator in another manner.

There are a number of different modes of operation that a voltageregulator power stage may use in order to reduce its conduction andswitching losses. For example, at a full or heavy load, the controllermay indicate to the voltage regulator to operate at a fixed switchingfrequency. Below a certain load limit, the voltage regulator may becontrolled to operate in a discontinuous conduction mode with a variablefrequency. In another mode, the voltage regulator may intentionally turnoff certain voltage regulator circuit components. For example, asynchronous switch in a buck converter may be shut down by thecontroller as the voltage regulator's output current approaches zero.There may be other operational modes that reduce power loss and increaseefficiency as well.

The controller may continue to monitor the device status as long as thedevice is operational (514), changing the voltage regulator operatingmode when appropriate (512).

FIG. 6 is a graph (600) which illustrates the results that may beachieved using embodiments of the load adaptive power delivery methodsdescribed herein. Line 602 indicates the efficiency of a voltageregulator using a conventional approach. The efficiency is optimized ata single maximum load point, and for all other operating loads, theperformance of the voltage regulator may be less efficient.

Line 604 indicates an improved efficiency using a load adaptive powerconversion scheme of one embodiment. When the device is operating at afirst load, in the range of zero to I_(—)1/P_(—)1, the voltage regulatoris controlled to operate in a first mode, thus giving an efficiencycurve of C1. Similarly, in each subsequent load range, the controllermay change the mode of the voltage regulator to give optimal efficiencycurves C2, Ck−1, and Ck. In some embodiments, the load curve (604) mayapproach a substantially linear load curve.

Thus, a method, apparatus, and system for load adaptive power deliveryare disclosed. In the above description, numerous specific details areset forth. However, it is understood that embodiments may be practicedwithout these specific details. In other instances, well-known circuits,structures, and techniques have not been shown in detail in order not toobscure the understanding of this description. Embodiments have beendescribed with reference to specific exemplary embodiments thereof. Itwill, however, be evident to persons having the benefit of thisdisclosure that various modifications and changes may be made to theseembodiments without departing from the broader spirit and scope of theembodiments described herein. The specification and drawings are,accordingly, to be regarded in an illustrative rather than a restrictivesense.

1. An apparatus comprising: a voltage regulator to supply an outputvoltage and an output current, the voltage regulator including acontroller coupled to the voltage regulator to sense the output voltageand output current, to receive load information comprising anoperational mode of a device and an estimated time period for which thedevice is expected to stay in the operational mode, and to dynamicallychange an operating mode of the voltage regulator based on the outputvoltage, the output current and the load information.
 2. The apparatusof claim 1, the voltage regulator comprising an input filter, at leastone power stage, and an output filter.
 3. The apparatus of claim 1,comprising a device monitor coupled to the controller, the loadinformation received by the controller from the device monitor.
 4. Theapparatus of claim 1, the load information comprising an upper and lowerlimit of power consumption for the device and the estimated time periodfor which the device is expected to stay in the operational mode.
 5. Theapparatus of claim 1, the mode of operation determined in response tothe load information, the output voltage, and the output current.
 6. Theapparatus of claim 1, the mode of operation comprising a fixed switchingfrequency mode of operation.
 7. The apparatus of claim 1, the mode ofoperation comprising a discontinuous conduction mode with variablefrequency mode of operation.
 8. A system comprising: a battery; avoltage regulator coupled to the battery and coupled to a device, thevoltage regulator operative to supply an output voltage and an outputcurrent; and a device monitor coupled to the device, the device monitoroperative to monitor load information for a device, the load informationcomprising an operational mode of the device and an estimated timeperiod for which the device is expected to stay in the operational mode;the voltage regulator including a controller operative to sense theoutput voltage and output current, to receive the load information fromthe device monitor, and to dynamically change an operating mode of thevoltage regulator based on the output voltage, the output current andthe load information.
 9. The system of claim 8, the device monitoroperative to store an operational mode of the device, an upper and lowerlimit of power consumption for the device and the estimated time periodfor which the device is expected to stay in the operational mode. 10.The system of claim 9, the device monitor comprising a register.
 11. Thesystem of claim 10, the device monitor operative to be updateddynamically.
 12. The system of claim 8, the voltage regulator operativeto change from a first mode of operation to a second mode of operationbased on the control signal.
 13. The system of claim 8, the devicecomprising a device having a variable load.
 14. The system of claim 13,the device comprising a hard disk drive.
 15. The system of claim 8, thecontroller operative to dynamically change the operating mode of thevoltage regulator based on the load information received from the devicemonitor.
 16. A method comprising: sensing an output voltage and anoutput current of a voltage regulator; receiving device informationcomprising load information for a device, the load informationcomprising an operational mode of a device and an estimated time periodfor which the device is expected to stay in the operational mode; anddynamically changing an operating mode of the voltage regulator based onthe device information, the output voltage and the output current. 17.The method of claim 16, the device information comprising informationregarding the operational mode of a device, a power range of the device,and a projected runtime of the device.
 18. The method of claim 16, themode of operation comprising a fixed switching frequency mode ofoperation.
 19. The method of claim 16, the mode of operation comprisinga discontinuous conduction mode with variable frequency mode ofoperation.
 20. The method of claim 16, comprising detecting a knowndevice behavior defined by a power consumption table and determining themode of operation using a predefined operational mode sequence.